Volume control



Feb. 23, 1932. w H, HAEFFER I 1,846,616

VOLUME CONTROL Filed April 4, 1951 Patented Feb. 23, 1932 UNITED STATES PATENT OFFICE WILLIAM E. SMITH, 01' PHILADELPHIA, PENNSYLVAN IA, ASSIGNOB TO ATWA'IEB KENT MANUFACTURING COMPANY, 01 PHILADELPHIA, PENNSYLVANIA, A COB- PORA'I'ION OF PENNSYLVANIA VOLUME CONTROL Application filed April 4, 1981. Serial- Ho. 527,889.

My invention relates to the control of volume of reproduction, articularly of radio receiving apparatus, and particularly to the prevention of electrical interaction between the components of a multiple volume control unit.

In accordance with my invention, adjustable impedances, particularly resistances, in different circuits of tube, s ecifically a radio 1 frequency amplifier, are isposed adjacent each other as in a common housing, for concurrent adjustment by the same operating member or shaft, and to prevent noises in the loud speaker, or equivalent, by movement of the control contacts of the impedances, a plate of conductive material is disposed between the impedances and preferably connected to a. point at ground potential.

My invention also resides in the features of 59 construction, arrangement and combination hereinafter described and claimed.

For an understanding of my invention and for illustration of the several forms it may take, reference is to be had to the accompanyin drawings, in which:

ig. 1 illustrates diagrammatically radio receiving apparatus utilizing the invention.

Fi 2 is an elevational view in section, of a mu tiple volume control unit utilized in the .9 system of Fig. 1.

Fig. 3 illustrates diagrammatically a further circuit arrangement utilizing my invention.

F i 4 is an elevatirmal view in section of a modfied form of a multiple volume-control unit utilized in the system of Fig. 3.

Fig. 5 illustrates diagrammatically a further circuit arrangement utilizing my invention.

Referring to Fig. 1, radio frequency signal ener im re$ed upon the input circuit of tube as ay an antenna system, not shown, or by a selective system interposed between the tube and an antenna, or a preceding amplifier, is amplified and impressed upon the tunable input circuit Tl, C1 of amplifier tube V1 which further amplifies the signal ener and impreses it upon the input circuit 0 a detector D directly, orv indirectly, throu h another amplifier stage inpluding the to V2 and its input circuit T2, C2. Theout ut of the detector is fed to a loud speaker S, preferably. after amplification by the audio frequency amplifier A.

Along the resistance R of suitably high magnitude, which shunts the primary turns P1 of coil T1, is adjustable a contact S for controlling the volume of reproduction by varying the effective signal voltage impressed upon t e grid g1 of amplifier V1. The control contact, as indicated, may be connected to the anode a of the tube V through a condenser K which is of low impedance to radio frequency currents as are also condensers The adjustable resistance R1 and fixed resistance R2 in series, are traversed by direct current derived from a suitable direct-current source, as batteries, or a rectifier-filter system. The screen grids s of the tubes V1 and V2 are connected to adjustable contact S1 of resistance R1, and the cathodes f of the same tubes are connected to a suitable int along resistance R2. As the contact 1 is moved along resistance R1, the difference of potential between the screen grids a and the cathodes f of the tubes is varied to change the amplification characteristic of the tubes and thus modify the am litude of reproduction by the loud speaker L3.

The volume control contacts S and S1 are mechanically coupled as generically indicated by the dash line 0:, for adjustment in unison by movement of the volume control knob A. The mechanical connections and circuitrelations are such that the simultaneous movement of the volume control contacts individually efiect volume changes which are the same in sense. Specifically, as the contacts S, S1 are moved upwardly from the position indicated, the volume increases, while conversely, if they are moved downwardly from the position shown, the volume decreases. The relative effectiveness of the resistances in changing volume varies for different positions of the contacts to ensure good quality of reproduction and high ratio of signal to tube noises, etc.

As shown in Fig. 2, the resistances R and R1 are disposed in a common housing H.

2. In radio receiving apparatus comprising a radio frequency amplifier having input and output systems, a detector having an input system coupled to said amplifier and an output system coupled to a soundreproducing de-vice,-a multiple volume control unit comprising a resistance in the input system of said amplifier, a resistance in the output system of said amplifier and disposed adjacent said first resistance, common actuating structure for contacts adjustable along said resistances, and a metal plate positioned between said resistances and connected to earth for preventing movement of said structure in control of volume from producing noises in said sound-reproducing device, resulting from rectification by said detector of electrical disturbances incident to' variation of said resistances.

3. In radio receiving apparatus comprising a radio frequency amplifier having input and output systems, a detector having an input system coupled to said amplifier and an output system coupled to a soundreproducing device, a multiple volume control unit comprising a resistance in the input system of said amplifier, a resistance in the output system of said amplifier, common actuating structure. for contacts ad ustable along said resistances, and metal plate struc ture interposed between said resistances and connected to earth for preventing impression electrical disturbances incident to adjustment of said second resistance on said first resistance and by rectification of said detector appearing as noise in said sound-reproducin device.

4. adio receiving apparatus comprising a thermionic tube for amplifying radio-frequency signal energy, an adjustable resistance, in the input circuitmf said tube for varying the signal voltage impressed on the grid thereof, a resistance for varying a direct-current difference of potential between the cathode of said tube and another electrode thereof disposed adjacent said first resistance, common structure for adjusting said resistances, and conductive plate structure interposed between said resistances and connected to earth.

5. Radio receiving apparatus comprising a thermionic tube for amplifying radio-frequency signal energy, an adjustable resistance n the input circuit of said tubefor varying the signal voltage impressed on the grid thereof, a resistance in the output system of said tube for varying the signal energy impressed on a subsequent detector circuit, and disposed adjacent said first resistance, common actuating structure for said resistance, and a conductive plate between said resistances connected to earth.

6. In radio receiving apparatus comprising a thermionic tube, a multiple-volume control unit comprising adjustable resistances connected in difierent circuits of said tube and positioned adjacent each other, common actuating structure for adjustment of said resistances and a metal plate structure disposed between said resistances and connected to earth.

7. Radio receiving apparatus comprising a screen-grid tube for amplifying radio-frequency signal energy, an adjustable resistance in the input circuit of said tube for varying the signal voltage impressed on the control-electrode thereof, an adjustable resist-- ance for varying the potential of the screen grid of said tube and disposed adjacent said first resistance, and conductive structure connected to earth and disposed between said resistances to isolate them electro-ma etically and electro-statically from each ot er.

8. Radio receiving apparatus comprising a. thermionic tube for amplifying radio-frequency signal energy, radio-frequency transformers in the input and output systems of said tubes, adjustable resistances in shunt to the primary windings of said transformers, a common housing for said resistances, a common actuating shaft for said resistances, and a metal plate within said housingbetween said resistors and connected to earth.

9. Radio receiving apparatus com a thermionic tube for amplifying ra quency signal energ, a housing, a grounded metal plate within said housin for dividing it into electro-magnetically and electro-stati cally isolated compartments, volume control resistances within separate compartments of said housing and included in the input and output systems of said tube respectively, and

rising 1o frea common actuating member for effecting concurrent ad ustment of said resistances.

10. Radio receiving apparatus comprising a thermionic tube for amplifying radio-frequency signal energy, a housing, adjustable resistances disposed within said housing and included in the input and output systems of said tube, and a common actuating member for said resistances, at least one of said resistances having a distortable, grounded contact plate for varying it and interposed between the resistances ele'ctro-magnetically and electro-statically to isolate them.

WILLIAM H. SOHAEFFER. 

